In a wide variety of computationally-capable devices, such as computers, digital cameras, cellular telephones, printers, etc., it is known for a host processor to execute one or more operations with the assistance of a co-processor. Typically, a co-processor is called upon to execute specialized or processing-intensive functions. For example, if the host processor requires one or more images to be rendered on a display screen, a graphics co-processor may be used to perform the rendering operations.
As further known in the art, co-processors typically include one or more processing components and dedicated memory (typically) used exclusively by the one or more processing components. For example, in the case of a graphics co-processor, it is known to use a dedicated memory for the purpose of establishing a frame buffer. Frame buffers are used as storage for image data to be rendered on a suitable display. With the recent advent of portable devices that incorporate video and/or graphics processing, reduced cost and size for constituent components that support such processing has become increasingly important. For example, in the case of graphics co-processors, the dedicated memory described above has been implementing using so-called embedded dynamic random access memory (EDRAM) which has the advantage of low cost and reduced physical dimensions. However, a drawback of EDRAM, including its significant use of power during normal operation, is the occurrence of substantial quantities of leakage current even when the device is not active. In portable, battery-operated devices, this can have a significant, deleterious impact on battery life.
Although other storage devices are available, such as static random access memory (SRAM), which offer less leakage current and therefore reduce battery drain, such devices are typically more expensive and have larger physical dimensions. Therefore, it would be advantageous to provide a co-processor architecture that provides the benefits of low cost, small physical dimension memory devices but that overcomes the leakage current problems typically associated with such devices.